Ampeg SVT III

Ampeg SVT-III, not the SVT 3 Pro. I believe it is a late 80s amp.Output transistors are mounted to the heatsink and are in the old school TO-3 package. These ones are MJ15023/MJ15022. Preamp is up front with three 12AX7s and the output section and power supply are towards the rear.

This is similarly rack-able like the SVT-II but with SS output section instead of six 6550s it’s way smaller and lighter. It did 358W at clipping into 4 ohms, 100 more watts than SVT II.

Main problem was the inductor at the output was physically damaged because of a drop, and then electronic damaged ensued from intermittent connection.The red wire wound inductor is in parallel with the 10 ohm/2W resistor. They are in series with the output. The 10 ohm resistor is blackened — it is burnt open. The inductor was broken loose from the PCB but still making contact. After a little use it rattled loose making an intermittent connection, frying the 10 ohm resistor and also burning the PCB traces underneath. It’s important to scrape all the charred remains off the PCB because it is now carbonized plastic and therefore can be conductive.Full schematic and parts list and all that here — https://drive.google.com/folderview?id=0B01EXvY0__YYeTZWZnRBang4T1k&usp=sharing